Pilot Research grant program: PA-01-038 Despite the most recent report on the risks of combined estrogen (E2) and progestin therapy on cardiovascular disease, there is still no evidence to suggest that E2 alone is not protective in these disease processes. This, morevover, stresses the importance of further studies to determine the precise role of E2 in mediating systemic and cellular function that may adversely be regulated in age-related disease. Renal disease is an underlying and/or contributing factor to cardiovascular and other age-related diseases. It is thus puzzling that little attention has been paid to examining the cause and treatment of agerelated renal disease. Age-related renal disease is associated with glomerulosclerosis and tubulointerstitial fibrosis; however the factors mediating these processes have thus far not been examined. Based on our preliminary data showing that the renal renin-angiotensin system (RAS) is downregulated with ovariectomy, we hypothesize that the protective role of E2 is partially mediated by downregulation of the RAS. Our studies also show that expression of enzymes involved in nitric oxide (NO) synthesis is downregulated with ovariectomy, and we hypothesize that the protective role of E2 will be mediated by upregulation of NO synthesis. Both Ang II and NO regulate cell proliferation and extracellular matrix (ECM) metabolism, the two major processes that are adversely affected and contribute to the development of glomerulosclerosis and tubulointerstitial fibrosis. Thus, our overall hypothesis is that E2 regulates the RAS and nitric oxide pathways and that the increased responsiveness of their specific target cells (proximal tubule and renal interstitial fibroblasts) contribute to the pathogenesis of age-related tubulointerstitial injury. Specific Aim 1will examine the functional changes in the aging kidney, due to abnormal regulation of the RAS and NO pathways: renal expression of the components of the cell-specific RAS and NOS will be measured by real-time PCR and Western analysis. Specific Aim 2 will examine the structural changes in the aging kidney, due to of the abnormal regulation of the RAS and NO pathways: tissue morphological changes, cell proliferation and ECM metabolism will be examined by immunohistochemistry, light miscrocopy, Western analysis and zymography. Knowledge gathered from these studies will contribute to our overall understanding of processes that are adversely affected with aging and may lead to development of novel therapeutic strategies to prevent age-related disease in women.